JP2001065303A - Steam turbine blade, manufacture of the same, steam turbine power generating plant and low pressure steam turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steam turbine blade capable of reducing the difference in tensile strength between a blade part and a dovetail, and having both of strength and proper toughness by specifying a length of the blade part with respect to a rotational speed of a blade, specifying the tensile strength of the dovetail, and forming the steam turbine blade out of specific Ti alloy. SOLUTION: In this steam turbine blade having a blade part 51 and a dovetail 52, a length of the blade part is set to be above 52 inches to a rotational speed of a blade of 3000 rpm or above 43 inches to 3600 rpm. The tensile strength at a room temperature, of the dovetail 52 is set to be above 100 kg/mm2. The steam turbine blade is formed out of Ti alloy having above 96% of the tensile strength at a room temperature, of the blade part 51. On the other hand, a hole 53 capable of inserting a pin, is formed on the dovetail 52. The blade part 51 is provided with an erosion shield 54, a tie boss 55 and a continuous cover 57. High capacity and high efficiency of a steam turbine power generating plant can be achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a steam turbine blade made of a Ti-based alloy, a method of manufacturing the same, a steam turbine power plant using the same, and a low-pressure steam turbine.

[0002]

2. Description of the Related Art Conventionally, in the last stage of a steam turbine low pressure, 3
3.5 inch long wing with 12Cr steel, 40 inch long wing with Ti
-6Al-4V is currently the longest 43 inch long wing in Japan and abroad as a 50 Hz compatible machine, and has high strength 12Cr.
Although steel is being developed, the demand for improving efficiency and increasing the size of the plant by increasing the length of the final blade stage is increasing, and further increasing the length of the blade is required. For that purpose, a lightweight and high-strength titanium alloy is indispensable in place of Ti-6Al-4V which has been used in the past.

[0003] Up to 40 inches long wing, tensile strength 95kg /
mm ² class titanium alloy was able to cope with the increase in centrifugal force due to sufficiently long wings, but for 45 inch or longer wings, a titanium alloy with a tensile strength of 100 kg / mm ² class is required . As a titanium alloy having a tensile strength of 100 kg / mm ² or more, there is an age-hardening β-type titanium alloy. However, this β-type titanium alloy has a drawback of low toughness. Has a problem. On the other hand, in the tough α + β type titanium alloy, the cooling rate during the solution treatment greatly affects the strength as the dovetail of the blade becomes thicker.
The strength obtained with small steel ingots is often not reproducible with large products, making it difficult to obtain a solid 100 kg / mm ² class titanium alloy.

In Japanese Patent Application Laid-Open No. 1-202389, the heat treatment conditions for Ti-6Al-6V-2Sn, which is an α + β type high-strength Ti alloy, are 10 to 60 ° C. below the β transformation point, that is, 867 to 917 ° C. And then 500 ~
Although it is said that the aging treatment is performed at 650 ° C., there is a problem that although the strength is obtained in the thin blade profile portion, the strength of the thick dovetail portion having a slow cooling rate cannot be secured.

Further, Japanese Patent Application Laid-Open No. 7-150316 discloses a turbine blade material of 3 to 5% Al, 2.1 to 3.7% V, Mo
A turbine blade made of a Ti-based alloy having 0.85 to 3.15% and 0.85 to 3.15% Fe is described, but no aging treatment is described.

[0006]

SUMMARY OF THE INVENTION The object of the present invention is to
As a steam turbine blade having a blade length above inches, smaller tensile strength difference between the blade portion and the dovetail portion, a room temperature tensile strength of the dovetail has a 100 kg / mm ² or more, moderate toughness with strength An object of the present invention is to provide a steam turbine blade made of a Ti-based alloy having an α + β type phase, a method of manufacturing the same, a steam turbine power plant, and a low-pressure steam turbine.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a steam turbine blade having a wing portion and a plurality of fork types 2 having inverted Christmas tree dovetails, wherein the wing portion length is larger than the rotation speed of the blade at 3000 rpm. At least 52 inches or 43 inches or more with respect to the rotation speed of 3600 rpm, and the tensile strength of the dovetil at room temperature is 100 kg / mm ^2.
As described above, the wing portion is preferably made of a Ti-based alloy having a tensile strength of at least 110 kg / mm ^{2 and at} least 96% of the tensile strength at room temperature of the blade.

[0008] The present invention provides a method for preparing Al 4-8%, V4
The Dovel has a tensile strength at room temperature of 100 kg / mm ² or more, preferably 110 kg / mm ² or more, and a V notch impact value (y) at room temperature of (−). 0.022x + 4.10) value determined by (kg-m) or more, or the wings tensile strength of the room temperature (x) is 105 kg / mm ² or more and V-notch impact value at room temperature (y) is (- 0.02x + 3.98) (kg-m) or more, and the tensile strength at room temperature of the dovetail is 96% or more of the tensile strength at room temperature of the wing portion. On the wings.

According to the present invention, the length of the wing portion is set to 30
At least 52 inches or 360 rpm for 00 rpm
At least 43 inches at 0 rpm and by weight Al4
-10%, V4-10% and Sn1-5%, and the wing has a room temperature tensile strength (x) of 10%.
V notch impact value (y) at 5 kg / mm ² or more and room temperature is (-
0.02x + 3.98) (kg-m)
Or the Dovetil has a room-temperature tensile strength (x) of 100 kg / mm ² or more and a V-notch impact value at room temperature.
(y) is equal to or more than the value (kg-m) obtained by (−0.022x + 4.10) in the steam turbine blade.

The present invention relates to a method of manufacturing a steam turbine blade made of a Ti-based alloy, in which A (605 ° C., 855 ° C.) and B (590) represented by (aging temperature, solution temperature) shown in FIG.
C, 790 ° C), C (410 ° C, 790 ° C) and D (4
(10.degree. C., 855.degree. C.), characterized by performing a solution treatment and an aging treatment by heating and water-cooling within a range connecting the four points. E (525 ° C, 855 ° C) and F (510
C, 790 ° C), G (410 ° C, 790 ° C), H (41
(0 ° C., 855 ° C.), characterized by applying a solution treatment and an aging treatment of heating and then blast cooling within a range connecting the four points. Before the final heat treatment, the dovetail portion is brought into a state close to the final shape. After roughing, J (685 ° C., 855 ° C.) represented by (aging temperature, solution heat temperature) shown in FIG. 3 of the present application,
K (585 ° C, 790 ° C), L (410 ° C, 790 ° C),
M (410 ° C., 855 ° C.), wherein a solution treatment and an aging treatment of heating and water cooling within a range connecting four points are performed, and before the final heat treatment, the dovetail portion is brought into a state close to a final shape. After roughing, N (575 ° C., 855) represented by (aging temperature, solution temperature) shown in FIG. 4 of the present application.
° C), O (560 ° C, 790 ° C), P (410 ° C, 79
(0 ° C.) and Q (410 ° C., 855 ° C.) in a range connecting the four points.

According to the present invention, in a steam turbine power plant including a high-pressure turbine, an intermediate-pressure turbine and a low-pressure turbine, the last-stage moving blade of the low-pressure turbine has a blade portion and a plurality of fork-shaped dovetiles. It is characterized by being constituted by steam turbine blades.

The present invention relates to a low-pressure steam turbine having a rotor shaft, a rotor blade implanted on the rotor shaft, a stationary blade for guiding the flow of steam to the rotor blade, and an internal casing holding the stationary blade. In the above, the rotor blade has a six-stage configuration in a symmetrical manner, and has a double-flow structure in which a first stage is implanted in a center portion of the rotor shaft, and a final-stage rotor blade includes the steam turbine blade described above. Is what you do.

[0013] After hot forging, the Ti-based alloy is heated and held in a temperature region having an α + β phase and is forcibly cooled (solutioned), whereby the α-phase and α 'martensitic two-phase structure is refined and homogenized. , High ductility and high toughness can be obtained. Further, in the subsequent aging treatment, α ′ martensite is decomposed into α + β2 phase, and a mixed grain form of pro-eutectoid α grains and old β grains in which α precipitates due to aging (age hardening), resulting in high tonicity. Strength and fatigue strength can be obtained. Solution temperature is Al 4-8%, V
Among Ti-based alloys containing 4 to 8% and Sn 1 to 4%, in particular, for the Ti-6% Al-6% V-2% Sn, the β transformation point (about 9%) is used.
A range of 800 to 900 ° C. below 27 ° C.) is appropriate.
In particular, 790 to 855 ° C. is more preferable depending on the combination. Above the β transformation point, the ductility and toughness decrease due to the coarsening of crystal grains and the decrease in the amount of pro-eutectoid α. On the other hand, if the solution temperature is too low, the hot forged structure remains and the amount of pro-eutectoid α increases, so that an appropriate strength cannot be obtained. The subsequent aging temperature is suitably in the range of 500 to 600 ° C.
As the aging temperature increases, the tensile strength decreases, and the ductility and toughness improve. In particular, a specific combination at 410 to 685 ° C. depending on the combination with the solution treatment temperature is suitable.

The reasons for the preferred ranges of the components of the Ti-based alloy used in the present invention are as follows.

Al: a typical α-stabilizing element, (α + β)
Is an indispensable additive element for the type Ti-based alloy. Al content is 4%
If it is less than (α + β), it is difficult to obtain an (α + β) type alloy, and it is difficult to obtain sufficient strength as a material. On the other hand, if the Al content exceeds 10%, Ti ₃ Al, which is an intermetallic compound, is generated, and the toughness is remarkably reduced.

In particular, the Al content is preferably 4 to 8%.

V is an important additive element that stabilizes the β phase and lowers the β transformation point. Suppress rapid formation and increase of α phase after annealing or solution treatment,
This has the effect of precipitating the phase finely. If the V content is less than 4%, the β transformation point cannot be sufficiently reduced, and the effect of stabilizing the β phase also decreases. Therefore, the effect of suppressing the formation of the α phase during annealing or after solution treatment is reduced. I can't get it. On the other hand, if the V content exceeds 10%, the stability of the β phase becomes too large, and it is difficult to obtain a preferable two-phase structure of (α + β), so that the strength becomes insufficient. In particular, the V content is preferably 4 to 8%.

Sn: has the effect of stabilizing the β phase and, at the same time, suppressing grain growth. Therefore, similarly to Al, it is important to suppress the rapid generation and increase of the α phase after annealing or solution treatment, to suppress the rapid generation and increase of the α phase, and to precipitate the α phase finely. Not only that, it is an additive component that has the effect of miniaturizing the entire structure and occupies an important position in increasing the strength. If the Sn content is less than 1%, the crystal grains become coarse during annealing or after solution treatment, and it is difficult to obtain the above-mentioned desired effects. On the other hand, if the Sn content exceeds 5%, the β phase becomes too stable, so that it is difficult to obtain a preferable two-phase structure, and a higher improvement in strength cannot be expected. In particular, the Sn content is preferably 1 to 4%.

As the last stage rotor blade of the low pressure turbine, the aforementioned T
i-alloy is used for wing lengths of 43 inches or more for 3600 rpm or 52 inches or more for 3000 rpm, especially 5 to 7% of Al, 5 to 7% of V, and 1 to 3 of Sn.
%, Fe 0.2 to 1.5%, O 0.20% or less, Cu 0.2%
An alloy composed of 3 to 1.5% with the remaining Ti being preferred is preferably subjected to the same heat treatment as described above.

The above requirements are applicable to the following inventions.

According to the present invention, in the above-described steam turbine power plant, the high-pressure turbine and the medium-pressure turbine or the high- and medium-pressure turbine have a steam inlet temperature to the first stage rotor blade of 538 to 538.
660 ° C (preferably 593-620 ° C, 620-630
C., 630 to 640 ° C.), the low-pressure turbine has a steam inlet temperature to the first stage rotor blade of 350 to 400 ° C., and the steam inlet temperature of the high-pressure turbine and the medium-pressure turbine or the high-medium-pressure turbine. The rotor shaft or rotor shaft, rotor blades, stator blades and inner casing which are exposed to all are composed of high-strength martensitic steel containing 8 to 13% by weight of Cr, or among them, the first or second stage of the rotor blades, Alternatively, it is preferable that up to three stages are made of a Ni-based alloy.

A high-pressure turbine, a medium-pressure turbine or a high-to-medium pressure turbine according to the present invention comprises a rotor shaft, a moving blade implanted on the rotor shaft, a stationary blade for guiding the flow of steam into the moving blade, and An inner casing for holding the stationary blades, wherein the temperature at which the steam flows into the first stage of the bucket is
8 to 660 ° C and a pressure of 250 kgf / cm ² or more (preferably 246 to 316 kgf / cm ² ) or 170 to 200 kgf / cm ²
cm ² , and the rotor shaft or the rotor shaft and at least the first stage of the moving blade and the stationary blade have respective steam temperatures (preferably 566 ° C., 593 ° C., 610 ° C., 625 ° C., 64
0 ℃, 650 ℃, ⁵ 10 at a temperature corresponding to the 660 ° C.)
Time creep rupture strength 10 kgf / mm ² or more (preferably 17 kgf / mm ² or more) Cr8.5~13 wt%
(Preferably 10.5 to 11.5% by weight) of a high-strength martensitic steel having a fully tempered martensite structure, or of which the first stage, the second stage or the third stage of the blade is Ni-based. Alloy, and the inner casing has a 10 ⁵ hour creep rupture strength of 10 kgf / mm ² or more (preferably 10.5 k) at a temperature corresponding to each steam temperature.
gf / mm ² or more) by heating a high-pressure steam turbine, a medium-pressure steam turbine or a high-pressure side turbine made of a martensitic cast steel containing 8 to 9.5% by weight of Cr,
It is preferable to use a high-to-medium pressure integrated steam turbine that is heated to a temperature equal to or higher than the high-pressure side inlet temperature and sent to the medium-pressure side turbine.

In the high-pressure turbine and the intermediate-pressure turbine or the high-intermediate-pressure integrated steam turbine, the first stage of the rotor shaft or at least one of the moving blade and the stationary blade is C by weight.
0.05 to 0.20%, Si 0.6% or less, preferably 0.1
5% or less, Mn 1.5% or less, preferably 0.05 to 1.
5%, Cr 8.5-13%, preferably 9.5-13%,
Ni 0.05 to 1.0%, V 0.05 to 0.5%, preferably 0.05 to 0.35%, at least one of Nb and Ta 0.01 to 0.20%, N 0.01 to 0. 0.1%, preferably 0.01 to 0.06%, Mo 1.5% or less, preferably 0.1%
0.5 to 1.5%, W 0.1 to 4.0%, preferably 1.0 to 1.0%
4.0%, Co 10% or less, preferably 0.5 to 10%,
B 0.03% or less, preferably 0.0005 to 0.03%
High strength martensitic steel containing 78% or more of Fe is preferable, and preferably corresponds to a steam temperature of 593 to 660 ° C, or C 0.1 to 0.25%, Si 0.6
%, Mn 1.5% or less, Cr 8.5-13%, Ni 0.5%
0.05 to 1.0%, V 0.05 to 0.5%, W 0.10 to 0.1%.
65%, at least one of Nb and Ta 0.01 to 0.2
0%, Al 0.1% or less, Mo 1.5% or less, N 0.02
High-strength martensitic steel with 5 to 0.1% and 80% or more Fe is preferred and preferably corresponds to 600 to less than 620 ° C. The inner casing is C by weight
0.06-0.16%, Si 0.5% or less, Mn 1% or less,
Ni 0.2-1.0%, Cr 8-12%, V 0.05-0.5.
35%, at least one of Nb and Ta 0.01 to 0.1
5%, N 0.01 to 0.8%, Mo 1% or less, W1 to 4
%, B 0.0005 to 0.003%, and is preferably made of a high-strength martensitic steel having 85% or more of Fe.

In the steam turbine power plant according to the present invention, in the high-pressure steam turbine, the moving blade has at least seven stages, preferably at least nine to twelve stages, and the first stage has a double flow. The bucket has a double-flow structure in which the rotor blades have six or more stages each symmetrically, and the first stage is implanted in the center of the rotor shaft.
The high pressure side moving blade has 6 stages or more, preferably 7 stages or more, more preferably 8 stages or more, and the medium pressure side moving blade has 5 stages or more, preferably 6 stages or more. It preferably has a double-flow structure in which each stage has 5 or more stages, preferably 6 or more stages, more preferably 8 to 10 stages, and the first stage is planted at the center of the rotor shaft.

In the low-pressure turbine according to the present invention, the steam inlet temperature to the first stage rotor blade is preferably 350 to 400 ° C., and the rotor shaft has a bearing center distance (L) of 6500 mm or more (preferably 6600 to 7500 mm) and The minimum diameter (D) at the part where the stator vanes are provided is 750 to 1300 mm
(Preferably 760 to 900 mm), and the (L /
D) 5 to 10, preferably 7 to 10 (more preferably 8.0 to 9.0) Ni-Cr-Mo-V low alloy steel containing 3.25 to 4.25% by weight of Ni described above. Is preferred.

[0026] In the low-pressure steam turbine according to the present invention, the blade length may be from 80 to 1 from upstream to downstream of the steam flow.
The rotor blade has a diameter of 300 mm, and a diameter of an implanted portion of the rotor blade of the rotor shaft is larger than a diameter of a portion corresponding to the stationary blade. An axial width of the implanted portion is preferably three stages or more on the downstream side as compared with the upstream side ( (Preferably 4 to 7 steps), and the ratio to the wing length is 0.2 to 0.8 (preferably 0.3 to 0.55), and the ratio from the upstream side to the downstream side is larger. The wing length of each adjacent stage is smaller on the downstream side than on the upstream side, and the ratio is 1.2 to 1.8 (preferably 1.0.
In the range of 4 to 1.6), the ratio is gradually increased on the downstream side, and the axial width of a portion of the rotor shaft corresponding to the stationary blade portion is preferably such that the downstream side is more upstream than the upstream side. Means 3 or more steps (more preferably 4 to 7 steps)
And the ratio of the moving blade to the adjacent downstream blade length is in the range of 0.2 to 1.4 (preferably 0.25 to 1.25, particularly 0.5 to 0.9). It is preferable that the ratio is gradually decreased toward the downstream side.

Hereinafter, other constituent materials of the low-pressure turbine will be described.

(1) The low-pressure steam turbine rotor shaft is 0.2 to 0.35% C, 0.1% or less Si, Mn
0.2% or less, Ni 3.25 to 4.25%, Cr 1.25 to
2.25%, Mo 0.1 to 0.6%, V 0.05 to 0.25%
Preferably, the alloy is a low-alloy steel having a fully tempered bainite structure and having the same structure as that of the high-pressure / medium-pressure rotor shaft described above. In particular, the amount of Si is 0.1.
01 to 0.05%, Mn 0.05 to 0.2%, P, S, A
It is preferable to use a raw material in which impurities such as s, Sb, and Sn are reduced as much as possible, and to use a super-cleaning production method in which raw materials having a small amount of impurities are used so that the total amount is 0.025% or less. P and S each 0.010% or less, S
n, As is preferably 0.005% or less, and Sb is preferably 0.001% or less.

(2) Other than the last stage of the blade for the low-pressure turbine and the nozzles, C 0.05-0.2%, Si 0.1-0.1%.
5%, Mn 0.2-1.0%, Cr 10-13%, Mo
A fully tempered martensitic steel having 0.04 to 0.2% is preferred.

(3) Both low and high pressure turbine internal and external cannons have C of 0.2 to 0.3%, Si of 0.3 to 0.7%, and M
Carbon cast steel with n1% or less is preferred.

(4) The main steam stop valve casing and the steam control valve casing are C 0.1-0.2%, Si 0.1-0.4.
%, Mn 0.2 to 1.0%, Cr 8.5 to 10.5%, Mo
0.3 to 1.0%, W 1.0 to 3.0%, V 0.1 to 0.3
%, Nb 0.03 to 0.1%, N 0.03 to 0.08%, B
A fully tempered martensitic steel containing 0.0005 to 0.003% is preferred.

[0032]

[Embodiment 1] As a steam turbine blade material according to the present invention, Al 5.89% by weight and V 5.98 by weight.
%, 0.33% Fe, 0.16% O, 2.31% Sn, C
An α + β-type Ti alloy consisting of 0.40% u and the balance Ti was used. The pro-eutectoid α phase has a solution temperature of 800 to
%, 37-46% at 850 ° C, 22-2 at 900 ° C
8%.

A forged product (400 mm, 190 mm) made of a dove-tiled material which is the thickest part of a long wing having a wing length of 45 inches
mm, 110 mm), and subjected to a solution treatment at 800 to 900 ° C. × 1 hour and an aging treatment at 500 to 600 ° C. × 4 hours, to a 1 / 2t portion corresponding to the center of the thickness of the dovetail portion and a wing portion. A test specimen was taken from the corresponding 1/4 t portion and subjected to a tensile test and an impact test at room temperature. The impact test was for a V notch and the cross-sectional area was 0.8 cm ² . The cooling in the solution treatment was of two types, water cooling and blast cooling.
The strength at the cooling rate was evaluated based on the position at which the test piece was collected.

Table 1 shows the tensile strength and the energy absorption of a 1/4 t portion of the water-cooled material by water cooling as a solution treatment.
Fig. 2 shows the tensile strength and the impact absorption energy of a 1 / 2t part.
In the １ ／ t portion where the cooling rate is high, the target strength of 110 kg / mm ² or more is satisfied in any of the heat treatments, but as the aging temperature increases, the strength decreases and the tolerance decreases. on the other hand,
In the 1 / 2t section where the cooling rate is slow, the solution solution at 900 ° C
Target strength of 110 kg / mm ² or more is not satisfied, but 800 ° C
And 500 ° C and 600 ° C, 850 ° C and 500 ° C and 60
The combination of the solution of 0 ° C. and the aging temperature is almost satisfactory. Also, as compared with the result of the 1 / 4t portion where the cooling rate is fast, the effect of the cooling rate is smaller as the solution heat temperature is lower, and the effect of the aging temperature is smaller as the solution heat temperature is higher. On the other hand, there is no remarkable difference in the impact absorption energy, and it is considered that the decrease in the fracture toughness value due to securing the strength is small. From these results, the relationship between the aging temperature and the solution temperature for obtaining the target strength is summarized. In the case of water cooling during solution, the hatched portions shown in FIG. 1, that is, A (605 ° C., 855 ° C.), B (590 ° C, 790
° C), C (410 ° C, 790 ° C), D (410 ° C, 85
(5 ° C.) is preferable.

As described above, the strength of the dovetail portion is about 99% less than the strength of the blade portion when the solution treatment temperature is 800 ° C. or less.
%, But when the temperature is increased to 850 ° C. and 900 ° C., 9
Since the temperature is lowered to 6% and 92%, the solution treatment temperature and the aging treatment temperature are adjusted as shown in FIG. 1 so that the strength of the dovetail portion is 96% or more of the blade portion.

[0036]

[Table 1]

[0037]

[Table 2]

Table 3 shows the tensile strength and the impact absorption energy of a 1 / 2t portion (the portion where the cooling rate is the slowest) by the impingement cooling. Similar to the water-cooled material, the relationship between the aging temperature and the solution temperature for obtaining the target strength is summarized. When the impingement cooling is performed during the solution treatment, the difference in strength between the dovetail portion and the wing portion can be reduced as shown in FIG. The hatched portion shown in FIG.
(525 ° C, 855 ° C), F (510 ° C, 790 ° C), G
(410 ° C, 790 ° C), H (410 ° C, 855 ° C)
The aging treatment temperature and the solution treatment temperature in the range connecting the points are preferable.

As shown in Table 3, the strength corresponding to the dovetail portion is 96% or more superior to that of the wing portion.

0.02% proof stress of 800 ° C. blast coolant is 1
93 to 101 kg / mm ² for the ｔt section, 93 to 101 kg / mm ^{2 for} the 1/2 t section
100kg / mm ² , 0.2% proof stress is 103 ~ 1 in 1 / 4t section
06kg / mm ^2, a 1 / 2t part in 96~107kg / mm ^2, even 15 to 17% either elongation, the drawing rate 1 / 4t
Part was 22-43%, and 1 / 2t part was 40-50%. Hv hardness was 335-356.

[0041]

[Table 3]

On the other hand, as a method of increasing the cooling rate of the thick portion, there is a method of roughing a dovetil before heat treatment, that is, a method of forming a slit corresponding to each fork when the dovetil is forked. . in this way,
Since the interval between the slits is smaller than 1 / 4t and there are about 5 to 10 slits, the cooling is performed from the front surface, and the overall cooling rate is equal to or higher than that of the 1 / 4t portion before processing. Therefore, based on the results in Table 1, the relationship between the aging temperature and the solution temperature for obtaining the target strength in the thick portion and the thin portion is summarized. In the case of performing the solution and water cooling after the slit processing, the hatching shown in FIG. Parts: J (685 ° C., 855 ° C.), K (5
85 ° C, 790 ° C), L (410 ° C, 790 ° C), M
(410 ° C., 855 ° C.) enables heat treatment in a range connecting four points. The same applies to the case of blast cooling during solution treatment. From the results in Table 3, the relationship between the aging temperature and the solution treatment temperature for obtaining the target strength is summarized. 4, that is, N (5
75 ° C, 855 ° C), O (560 ° C, 790 ° C), P
(410 ° C., 790 ° C.) and Q (410 ° C., 855 ° C.) can be heat-treated in a range connecting the four points.

Incidentally, the dovetail shape includes a fork type, an inverted Christmas tree type, and a saddle type.

FIG. 5 is a graph showing the relationship between the tensile strength of 1 / 2t and 1 / 4t. As shown in FIG. 5, when the solution heat treatment temperature was 800 ° C. and 850 ° C., the difference due to the effect of the thickness at the solution heat treatment temperature was small.
The strength at a thickness of / 2t is 96.0% or more. But 9
The solution treatment at 00 ° C. is affected by the wall thickness.
If it is less than 4.4%, the strength is undesirably reduced.

FIG. 6 is a graph showing the relationship between the impact absorption energy (y) and the tensile strength (x) at 1/4 t corresponding to the thickness of the wing. The lower line is y = -0.02x + 3.9
8, the upper limit line corresponds to y = −0.02x + 4.12, and the difference in wall thickness of the Ti-based alloy in this embodiment is obtained by setting the portion corresponding to the wing portion within the range of these lines. Can be obtained with less influence of the blade.

FIG. 7 shows a half corresponding to the dovetail thickness.
It is a diagram which shows the relationship between the impact absorption energy (y) and the tensile strength (x) at t. The lower line is y = -0.022x
+4.10, and the upper limit line is y = −0.022x +
The Ti-based alloy in this embodiment corresponds to 4.35, and the portion corresponding to the dovetail is within the range of these lines, so that a blade having a small difference in tensile strength and shock absorption energy from the above-mentioned wing portion can be obtained. Obtainable.

Furthermore, the impact absorption energy values at 1 / 2t and 1 / 4t are higher in the wing portion of the water-cooled material than in the dove-til portion, and higher in the dove-til portion of the blast coolant than in the wing portion. It is high within 5%.

Embodiment 2 FIG. 8 is a perspective view of the last stage steam turbine blade of a low pressure turbine for a steam turbine having a blade length of 43 inches and a steam temperature of 538 to 650 ° C. for 3600 rpm. The dovetail 52 is formed by eight forks, nine at a wing length of 46 inches. In this embodiment, the Ti-based alloy described in Embodiment 1 is used. In particular, the dovetail portion has a tensile strength of 110 kg / mm ² or more, and the dough portion has a tensile strength of 96% or more of the wing portion. It is preferable to use one that does. 53 is a hole for inserting a pin, 54 is an erosion shield, V10-20%,
Cr 1.5-5%, Al 1.5-5% and Sn 1.5-5
% Of Ti-based alloy or stellite containing
A Co-based alloy containing 20 to 35% of r, 10 to 25% of W, and 0 to 10% of Fe is brazed or electron beam welded.
The former Ti-based alloy was used. 57 is a continuous cover. 55 is a tie boss.

An example of manufacturing a turbine blade according to this embodiment will be described below.

First, an ingot having a composition equivalent to that of the alloy shown in Example 1 was roughly forged into a round bar material at about 850 ° C. in the α + β temperature range, and then a wing portion and a dovetail portion were stamped at the same temperature. A wing material of similar shape was formed. Each part had a thickness of about 1.3 times the final finished size. Next, the temperature was maintained at 850 ° C. for 1 hour, and the whole was put into water to perform quenching. After quenching, machined to near final shape by NC processing, then 15% V, 3% by weight
A Ti-based alloy plate containing Cr, 3% Al and 3% Sn was brazed to the leading edge at the tip of the blade. Next, the wing was fixed to a jig having a predetermined profile shape and heated for 4 hours at 500 ° C. for aging while being forcibly restrained. The erosion shield 54 is pre-
It is oil quenched after heating for one minute.

After the above-mentioned final heat treatment, the final shape of the blade profile, the blade implantation portion and its pin insertion hole are processed by final machining, and the product is obtained. The tensile strength of the wing-implanted portion with respect to the wing portion of this example was 98% or more, and the impact value was equivalent.

The wing implant 52 of this embodiment is of eight fork type, and has three pin insertion holes for one fork. In addition, the tip of the wing 51 viewed from the side in FIG.
A continuous cover 57 is provided in the same manner as described above, and is formed in a ring shape around the entire circumference in contact with each other. And the wings 5
One implant is substantially parallel to the axial direction of the rotor shaft, but its tip is about 75.
It is formed to be twisted so as to cross 5 times. The continuous cover 57 has the same composition as the wing material, and
Corresponds to the thickness of

In the case of 3000 rpm, a blade having a wing length of 52 inches or more can be manufactured in the same manner as this embodiment. This wing has nine forks.

[Embodiment 3] FIG. 9 is a side view of an inverted Christmas tree type wing-implanted portion instead of a fork type. The steam turbine blade shown in this drawing is the same as that of FIG. 8 except that the type of the blade implant 52 is different, and other structures are the same. Also in this embodiment, the Ti-based alloy of the first embodiment is used. As shown in the figure, the wing implant 52 has four straight projections on both sides, and the wings are implanted and fixed on the rotor shaft by high-speed rotation by the projections. A groove having the same space as this outer shape is formed in the rotor shaft so as to be implanted along the axial direction of the rotor shaft. Further, the wings 51
A continuous cover 57 is provided at the tip of
The wing portion of the implanted portion is formed substantially parallel to the axial direction of the rotor shaft, and the tip portion is formed so as to intersect about 75.5 degrees with the axial direction as described above.

Also in this embodiment, the rotational speed is 3600 rpm.
With a wing length of 43 inches, 46 inches, and 48 inches, and a rotation speed of 3000 rp.
It is possible to form a material having a size of 52 inches or more with respect to m. The above-mentioned projection has four steps up to 46 inches, but 48 steps.
Five steps for inches or more.

Further, the erosion shield 54 is made of a Ti-based alloy plate or a Co-based alloy plate in the same manner as described above, and is similarly joined.

Embodiment 4 Table 4 shows the main specifications of a steam turbine of 625 ° C. and 1050 MW according to the present invention. In this embodiment, the blade length of the last stage rotor blade in a cross-compound type four-flow exhaust low-pressure turbine is 43 inches, A is 3600 rpm for two HP-IP and LP, and B is H
P-LP and IP-LP have the same rotation speed of 3600 rpm, respectively, and are composed of the main materials shown in Table 4 in the high temperature part. The steam temperature of the high pressure section (HP) is 625
° C, a pressure of 250 kgf / cm ² , the steam temperature of the intermediate pressure part (IP) is heated to 625 ° C by a reheater,
It is operated at a pressure of 65 kgf / cm ² . The low-pressure section (LP) has a steam temperature of 400 ° C and is below 100 ° C, 722mmH
g of vacuum and sent to the condenser.

In this embodiment, the distance between the bearings of the high-pressure turbine and the intermediate-pressure turbine connected in tandem and the distance between the bearings of the two low-pressure turbines connected in tandem with respect to the blade length of the last stage rotor blade of the low-pressure turbine are described. Total is about 3
It is 1.5m, the ratio is 28.8, and it is compact.

Further, the distance between the bearings in which the high-pressure turbine and the medium-pressure turbine are connected in tandem with respect to the rated output (MW) of the steam turbine power plant in this embodiment, and the distance between the bearings of the two low-pressure turbines connected in tandem. The ratio of the total distance (mm) of the distances is 30.

[0060]

[Table 4]

FIG. 10 is a cross-sectional view of the high-pressure and medium-pressure steam turbines in turbine configuration A in Table 4. The high-pressure steam turbine is provided with a high-pressure axle (high-pressure rotor shaft) 23 in which high-pressure moving blades 16 are implanted in a high-pressure inner casing 18 and a high-pressure outer casing 19 outside thereof. The high-temperature and high-pressure steam is obtained by the above-mentioned boiler, passes through the main steam pipe, and the flange constituting the main steam inlet, the elbow 25 and the main steam inlet 28.
Through the nozzle box 38 to the first-stage double-flow moving blade. The first stage has a double flow, and eight stages are provided on one side. A stationary blade is provided for each of these moving blades. The blade is a saddle-type dovetil type, double tinon, and the first stage blade length is about 35 mm. The distance between the axles is about 5.8 m, the diameter of the smallest part corresponding to the stationary blade part is about 710 mm, and the ratio of the length to the diameter is about 8.2.

In the present embodiment, the materials shown in Table 7 described later are used for the first stage blade and the first stage nozzle, and the other blades and nozzles do not contain W, Co and B.
% Cr-based steel. The blade length of the rotor blade in this embodiment is 35 to 50 mm in the first stage and becomes longer in each stage from the second stage to the last stage. Particularly, the length from the second stage to the last stage depends on the output of the steam turbine. The length is 65 to 180 mm, the number of stages is 9 to 12, and the length of the wing of each stage is 1.
The length is increased at a rate of 10 to 1.15, and the rate is gradually increased on the downstream side.

The high-pressure turbine in this embodiment has a distance between bearings of about 5.3 m, and the ratio of the distance between bearings to the blade length of the last stage rotor blade of the low-pressure turbine is 4.8. The ratio of the distance (mm) between bearings of the high-pressure turbine to the rated output (MW) of the power plant is 5.0.

The medium-pressure steam turbine rotates the generator discharged from the high-pressure steam turbine together with the high-pressure steam turbine by the steam heated by the reheater to 625 ° C. at a speed of 3000 revolutions / min. Rotated. The medium pressure turbine has a medium pressure inner second casing 21 and a medium pressure outer casing 22 similarly to the high pressure turbine.
7 is provided with a stationary vane. The moving blades 17 have two flows in six stages, and are provided on the left and right substantially symmetrically with respect to the longitudinal direction of the medium pressure axle (medium pressure rotor shaft). The distance between the bearing centers is about 5.8 m, the length of the first stage blade is about 100 mm, and the length of the last stage blade is about 230 mm. The first and second stage dovetails are inverted chestnut type. The diameter of the rotor shaft corresponding to the stationary blade before the last stage rotor blade is about 630 mm, and the ratio of the distance between bearings to the diameter is about 9.2 times.

In the rotor shaft of the intermediate-pressure steam turbine according to the present embodiment, the axial width of the rotor blade implanted portion gradually increases in three stages from the first stage to the fourth stage, the fifth stage, and the last stage.
The width at the last stage is about 1.4 times larger than that at the first stage.

The diameter of the rotor shaft of the steam turbine according to the present invention is small in a portion corresponding to the stationary blade portion, and the width of the rotor shaft is divided into four stages in accordance with the first-stage moving blade, the second to third stages and the last-stage moving blade. The width of the latter in the axial direction with respect to the former is reduced to about 0.75 times.

In this embodiment, a 12% Cr-based steel containing no W, Co and B is used except that the materials shown in Table 7 described later are used for the first stage blade and the nozzle. The length of the blade portion of the moving blade in this embodiment is longer at each stage as it goes from the first stage to the last stage, and the length from the first stage to the last stage is 60 to 300 mm depending on the output of the steam turbine.
In the nine stages, the length of the wing portion of each stage is longer at a ratio of 1.1 to 1.2 as the length on the downstream side is adjacent to the upstream side.

The implanted portion of the moving blade has a diameter larger than that of the portion corresponding to the stationary blade, and the implant width is larger as the blade length of the moving blade is larger. The ratio of the width to the blade length of the rotor blade is 0.1 in the first stage to the last stage.
35 to 0.8, and gradually decreases from the first stage to the last stage.

The intermediate pressure turbine in this embodiment has a bearing distance of about 5.5 m, and the ratio of the intermediate pressure turbine bearing distance to the blade length of the last stage moving blade of the low pressure turbine is as follows.
The ratio of the distance between bearings (mm) to the rated output (MW) of the power plant is 5.2.

The turbine blades implanted in the first stage of the high-pressure turbine are of the saddle type, and the turbine blades implanted in the second stage of the high-pressure turbine and all stages of the medium-pressure turbine are of the inverted Christmas tree type.

FIG. 11 is a sectional view of a low-pressure turbine having a rotation speed of 3600 rpm. The low pressure turbine is connected in two tandems and has almost the same structure. Each of the moving blades 41 has eight stages on the left and right sides and is substantially symmetrical on the left and right sides, and stationary blades 42 are provided corresponding to the moving blades. The steam turbine blade made of a Ti-based alloy having a blade length of 43 inches double tinon shown in Example 2 or 3 was used as the last stage rotor blade. The nozzle box 45 is of a double flow type.

For the rotor shaft 44, forged steel of the super-tempered bainite steel which is super-cleaned as shown in Table 5 is used. Various characteristics of the steel shown in Table 5 were examined using a 5 kg steel ingot. These steels are heated at 840 ° C. for 3 hours after hot forging,
After quenching at 00 ° C./h, tempering at 575 ° C. × 32 h is performed. Table 6 shows the characteristics at room temperature.

[0073]

[Table 5]

[0074]

[Table 6]

Each sample has a fully tempered bainite structure. 0.02% yield strength 80 kg / mm ² or more, a 0.2% proof stress 87.5kg / mm ² or more, a tensile strength of 100 kg / mm ² or more, V
Notch impact value of 10 kg-m or more, FATT has a high strength and high toughness of -20 ° C or less, and satisfies the implantation of 46 inches as well as a wing length of 43 inches or more as the last stage rotor blade of this embodiment. Was something. No. 4 having a slightly higher Cr content has a lower strength, and the Cr content is preferably up to about 2.20%. In particular, the 0.2% proof stress (y) is more than (1.35x-20), more preferably (1.35x) than the 0.02% proof stress (x).
The value is preferably equal to or more than the value obtained by -19).

The rotor blades and stationary blades other than the last stage have M
A 12% Cr steel containing 0.1% of o is used. 0.25% cast steel is used for the inner and outer casing materials.
The center-to-center distance of the bearing 43 in this embodiment is 7500 mm
And the diameter of the rotor shaft corresponding to the stationary blade portion is about 128
0 mm, and the diameter at the blade implantation part is 2275 mm. The distance between the bearing centers for this rotor shaft diameter is about 5.
9.

In this embodiment, the continuous cover 57 is formed by cutting after forging the whole. In addition, the continuous cover 57 can also be integrally formed mechanically.

In the low-pressure turbine according to the present embodiment, the axial width of the moving blade implantation portion is from the first stage to the third stage, the fourth stage, the fifth stage, the sixth stage, and the eighth stage.
The width gradually increases in four stages, and the width of the last stage is about 2.5 times larger than the width of the first stage.

The diameter of the portion corresponding to the stationary blade portion is reduced, and the axial width of the portion is gradually increased in the third, fifth, sixth, and seventh stages from the first stage blade side. The width of the last stage is about 1.
9 times larger.

The rotor blades in this embodiment have eight stages, and the length of the blades increases in each stage from the initial stage of approximately 3 ″ to the final stage of 43 ″, and from the initial stage to the final stage depending on the output of the steam turbine. The length of the stage is 90 ~ 1270mm, 8 or 9 stages, and the wing length of each stage is 1.3 ~ 1.6 times as long as the downstream side is adjacent to the upstream side. I have.

The implanted portion of the moving blade has a diameter larger than that of the portion corresponding to the stationary blade, and the implanted width increases as the blade length of the moving blade increases. The ratio of the width to the blade length of the rotor blade is 0.1 in the first stage to the last stage.
15 to 0.19, and gradually decreases from the first stage to the last stage.

The width of the rotor shaft corresponding to each stationary blade is gradually increased in each stage from the first stage and the second stage to the last stage and the front stage. The ratio of the width to the blade length of the rotor blade is 0.25 to 1.25, and decreases from upstream to downstream.

In this embodiment, two low pressure turbines are connected in tandem, and the total distance between bearings is about 18.3 m.
And the ratio of the total distance between the bearings of the two low-pressure turbines connected in tandem to the blade length of the last stage rotor blade of the low-pressure turbine is 16.7, and the rated output of the power plant is 1050 (MW). Tandem bound to 2
The ratio of the sum of the distances (mm) between the bearings of the low-pressure turbine at both ends of the table is 17.4. In addition to the present embodiment, the steam inlet temperatures to the high-pressure steam turbine and the medium-pressure steam turbine are 610 ° C., and the steam inlet temperatures to the two low-pressure steam turbines are 385 ° C.10
The same configuration can be applied to a 00MW class large-capacity power plant.

The high-temperature high-pressure steam turbine plant in this embodiment is mainly composed of a coal-fired boiler, a high-pressure turbine, a medium-pressure turbine, two low-pressure turbines, a condenser, a condensate pump, a low-pressure feedwater heater system, a deaerator, and a booster pump. , Feed water pump,
It is composed of a high pressure feed water heater system. That is, the ultra-high-temperature and high-pressure steam generated in the boiler enters the high-pressure turbine to generate power, is reheated again in the boiler, and enters the medium-pressure turbine to generate power. The intermediate-pressure turbine exhaust steam enters the low-pressure turbine to generate power, and then condenses in the condenser. This condensate is sent to the low pressure feed water heater system and deaerator by the condensate pump. The feedwater degassed by this deaerator is sent to a high-pressure feedwater heater by a booster pump and a feedwater pump to be heated, and then returned to the boiler.

Here, in the boiler, the feed water passes through a economizer, an evaporator, and a superheater to become high-temperature and high-pressure steam. On the other hand, the boiler combustion gas that heated the steam exited the economizer,
Enter the air heater to heat the air. Here, the feedwater pump is driven by a feedwater pump drive turbine that operates with the extracted steam from the medium pressure turbine.

In the high-temperature and high-pressure steam turbine plant configured as described above, the temperature of the feedwater exiting the high-pressure feedwater heater system is much higher than the feedwater temperature in the conventional thermal power plant, so that the boiler is inevitable. The temperature of the combustion gas exiting the economizer will also be much higher than in conventional boilers. Therefore, heat is recovered from the boiler exhaust gas so as not to lower the gas temperature.

Further, instead of this embodiment, a tandem compound power generation system in which one low-pressure turbine is connected in tandem to each of the same high-pressure turbine and medium-pressure turbine, and one generator is connected to each of them to generate power. A plant can be similarly configured. In the generator of the present embodiment having an output of 1050 MW, a shaft having a higher strength is used as the generator shaft. In particular, C 0.15 to 0.30
%, Si 0.1 to 0.3%, Mn 0.5% or less, Ni 3.2%
5 to 4.5%, Cr 2.05 to 3.0%, Mo 0.25 to 0.6
0% has a fully tempered bainite structure containing V0.05～0.20% at room temperature tensile strength of 93kgf / mm ² or more, particularly 100 kgf / mm ² or more, 50% FATT is 0 ℃ or less,
In particular, it is preferable that the temperature be -20 ° C or lower, and 21.2KG
And the total amount of P, S, Sn, Sb and As as impurities is 0.02.
It is preferable that the Ni / Cr ratio be 5% or less and the Ni / Cr ratio be 2.0 or less.

The high-pressure turbine shaft has a structure in which nine stages of blades are planted around the multi-stage first stage blade planting portion. The medium-pressure turbine shaft has a multi-stage blade provided on the left and right with approximately six stages of symmetrical blade installation portions, and substantially centered on the center. Although the rotor shaft for the low-pressure turbine is not shown, a center hole is provided in any of the rotor shafts of the high-pressure, medium-pressure, and low-pressure turbines, and through this center hole, the presence or absence of a defect is determined by ultrasonic inspection, visual inspection, and fluorescence inspection. Is inspected. Further, the inspection can be performed by ultrasonic inspection from the outer surface, and the center hole may not be provided.

Table 7 shows the chemical compositions (% by weight) used for the main parts of the high-pressure turbine, medium-pressure turbine and low-pressure turbine according to the power plant of the embodiment. In this embodiment, since the high-temperature portion of the high-pressure portion and the intermediate-pressure portion are all made to have a thermal expansion coefficient of about 12 × 10 ⁻⁶ / ° C. having a ferrite crystal structure, there is no problem due to the difference in the thermal expansion coefficient. Did not.

For the rotor shafts of the high-pressure turbine and the medium-pressure turbine, 30 tons of the heat-resistant cast steel described in Table 7 (% by weight) was melted in an electric furnace, carbon was deoxidized in a vacuum, cast into a mold, and forged. Electrode rods were prepared, electroslag was re-dissolved as the electrode rods from the upper part to the lower part of the cast steel, and forged into a rotor shape (diameter 1050 mm, length 3700 mm) and molded. The forging was performed at a temperature of 1150 ° C. or less in order to prevent forging cracks. After annealing, the forged steel is heated to 1050 ° C., subjected to water spray cooling and quenching, tempered twice at 570 ° C. and 690 ° C., and cut into a final shape. In the present embodiment, the upper side of the electroslag steel ingot is the first stage blade side, and the lower side is the last stage side. Each rotor shaft has a center hole, and the center hole can be eliminated by reducing impurities. The blades and nozzles of the high-pressure part and the medium-pressure part were prepared by melting the heat-resistant steel listed in Table 7 in a vacuum arc melting furnace and forging into blade and nozzle material shapes (width 150 mm, height 50 mm, length 1000 mm). Molded. This forging is to prevent forging cracks,
The test was performed at a temperature of 1150 ° C. or less. In addition, this forged steel
Oil quenching treatment by heating to 0 ° C, tempering at 690 ° C,
Next, it was cut into a predetermined shape.

The inner casing, the main steam stop valve casing, and the steam control valve casing of the high pressure section and the medium pressure section are shown in Table 7.
Was melted in an electric furnace, and after ladle refining, it was cast into a sand mold to produce. By performing sufficient refining and deoxidation before casting, a casting free of casting defects such as shrinkage cavities was obtained. Weldability evaluation using this casing material
The measurement was performed according to IS Z3158. The pre-heating, inter-pass and post-heating onset temperatures were 200 ° C., and the post-heating was 400 ° C. × 30 minutes. No weld crack was observed in the material of the present invention, and the weldability was good.

[0092]

[Table 7]

Table 8 shows the mechanical properties and heat treatment conditions of the main members of the high temperature steam turbine made of ferritic steel described above by cutting.

As a result of examining the center part of the rotor shaft, the characteristics (62
5 ° C., 10 ⁵ h strength ≧ 10 kgf / mm ² , 20 ° C. shock absorption energy ≧ 1.5 kgf-m). This demonstrated that a steam turbine rotor usable in steam at 620 ° C. or higher can be manufactured. Also, as a result of investigating the characteristics of this blade, the characteristics (625 ° C., 10 ⁵
h strength ≧ 15 kgf / mm ² ). This demonstrated that a steam turbine blade usable in steam at 620 ° C. or higher can be manufactured.

Further, as a result of investigating the characteristics of this casing, it was found that the characteristics (625 ° C., 10 ⁵ h strength ≧ 10 kgf / mm ² , 20 ° C. shock absorption energy ≧ 1 kgfm) required for the high-pressure and intermediate-pressure turbine casings were sufficient. Satisfaction and weldability were confirmed. This demonstrated that a steam turbine casing usable in steam at 620 ° C. or higher can be manufactured.

[0096]

[Table 8]

In the present embodiment, Cr-Mo low alloy steel was build-up welded on the journals of the high and medium pressure rotor shafts to improve the bearing characteristics. The overlay welding is as follows.

A covered arc welding rod (diameter: 4.0φ) was used as the test welding rod. Table 9 shows the chemical composition (% by weight) of the deposited metal obtained by welding using the welding rod. The composition of the deposited metal is almost the same as the composition of the welding material. The welding conditions are welding current 170A, voltage 24V, speed 26cm / min.
It is.

[0099]

[Table 9]

As shown in Table 10, the overlay welding was carried out on the surface of the base material to be tested by combining the welding rods used for each layer and eight layers. The thickness of each layer was 3-4 mm, the total thickness was about 28 mm, and the surface was ground about 5 mm.

The welding conditions were preheating, inter-pass, stress relief annealing (SR) start temperature of 250 to 350 ° C., and SR processing conditions of 630 ° C. × 36 hours.

[0102]

[Table 10]

[0103] In order to confirm the performance of the welded portion, the plate material was similarly overlaid and subjected to a side bending test at 160 °, but no crack was found in the welded portion.

Further, a bearing sliding test by rotation in the present invention was performed.
It was also excellent in oxidation resistance.

Instead of this embodiment, a tandem type power plant in which a high-pressure steam turbine, an intermediate-pressure steam turbine, and one or two low-pressure steam turbines are connected in tandem to rotate at 3600 rpm, and turbine configuration B in Table 4 are also used. The high-pressure turbine, the intermediate-pressure turbine and the low-pressure turbine of the present embodiment can be similarly combined and configured.

[Example 5] Table 11 shows that the main steam temperature was 538 ° C.
/ 566 ° C, rated output 700 MW is the main specification of the steam turbine. In this embodiment, a tandem compound double flow type, the last stage blade length in a low pressure turbine is 46 inches, an HP (high pressure) / IP (intermediate pressure) integrated type, and an LP1
The stage (C) or the two units (D) has a rotation speed of 3600 rpm, and is constituted by the main materials shown in the table in the high temperature part. High-pressure section (HP) steam temperature is 538 ℃, 246kg
f / cm ² , and the steam temperature in the medium pressure section (IP) is 5
Heated to 66 ° C by a reheater, 45 to 65 kgf / cm
Operated at a pressure of ² . Low pressure section (LP) has a steam temperature of 4
It enters at 00 ° C and is sent to the condenser under a vacuum of 722 mmHg below 100 ° C.

In the steam turbine power plant according to the present embodiment, which includes a high-to-medium pressure integrated turbine in which a high-pressure turbine and a medium-pressure turbine are integrated and two low-pressure turbines in tandem, the distance between bearings is about 22.7 m. The distance between the bearings of the high-to-medium pressure integrated turbine and the tandem coupling to the blade length (1168 mm) of the last stage rotor blade of the low pressure turbine
The ratio of the sum of the distances between the bearings of the low-pressure turbines of the table is 19.
4

Further, in this embodiment, the steam turbine power plant including the high-medium pressure integrated turbine in which the high-pressure turbine and the medium-pressure turbine are integrated and one low-pressure turbine is:
The distance between the bearings is about 14.7 m, and the ratio of the total distance between the bearings of the high and medium pressure integrated turbine and the distance between the bearings of one low pressure turbine to the blade length (1168 mm) of the last stage rotor blade of the low pressure turbine is 12 .6. The ratio of the sum of the distance between the bearings of the high and medium pressure integrated turbine and the distance between the bearings of one low pressure turbine to 1 MW at a rated output of 700 MW of the power plant is 21.0.

[0109]

[Table 11]

FIG. 12 is a cross-sectional view of the high-pressure / intermediate-pressure integrated steam turbine. The high-pressure side steam turbine is a high-to-medium pressure axle (high-pressure rotor shaft) 33 in which high-pressure moving blades 16 are implanted in a high-pressure inner casing 18 and a high-pressure outer casing 19 outside thereof.
Is provided. The high-temperature and high-pressure steam is obtained by the boiler, passes through the main steam pipe, passes through the main steam inlet 28 through the flange and elbow 25 constituting the main steam inlet, and is guided from the nozzle box 38 to the first stage rotor blades. . The steam enters from the center of the rotor shaft and flows toward the bearing. The rotor blades are provided in eight stages on the high pressure side on the left side in the figure and six stages on the medium pressure side (about half the right side in the figure). A stationary blade is provided for each of these moving blades. The blade is saddle type or getter type,
Dovetil type, double tinon, high pressure side first stage blade length about 4
0 mm, and the first stage blade length on the medium pressure side is 100 mm. The length between the bearings 43 is about 6.7 m 2, the diameter of the smallest part corresponding to the stationary blade portion is about 740 mm, and the ratio of the length to the diameter is about 9.0.

The first stage and the last stage of the rotor blade implant root portion of the high pressure side rotor shaft have the largest width at the first stage, the second stage to the seventh stage are smaller than that, and 0.40 to 0.56 times the first stage. Are the same size, the last stage is between the first stage and the size of the second to seventh stages, and is 0.46 to 0.62 times the size of the first stage.

On the high pressure side, the blades and nozzles were made of 12% Cr steel shown in Table 7 above. The blade length of the rotor blade in this embodiment is 35 for the first stage.
The length from the second stage to the final stage is in the range of 50 to 150 mm depending on the output of the steam turbine, and the number of stages is 7 to 12 mm. It is within the range of the stage, and the length of the wing portion of each stage is 1.05 to 1.35 as the length that the downstream side is adjacent to the upstream side.
The ratio becomes longer within the double range, and the ratio gradually increases on the downstream side.

The medium-pressure steam turbine rotates the generator discharged from the high-pressure steam turbine together with the high-pressure steam turbine by the steam heated again by the reheater to 566 ° C., and is rotated at a rotation speed of 3600 rpm. You. The intermediate pressure side turbine has an intermediate pressure inner second casing 21 and an intermediate pressure outer casing 22 similarly to the high pressure side turbine, and a stationary blade is provided to oppose the intermediate pressure moving blade 17. Medium pressure blade 17 is 6
It is a step. The first stage blade length is about 130mm, and the last stage blade length is about 26
0 mm. Dovetil is an inverted chestnut type.

In the rotor shaft of the intermediate-pressure steam turbine, the axial width of the root portion of the rotor blade implantation is largest at the first stage, smaller at the second stage, smaller at the third to fifth stages smaller than the second stage, and the same. The width of the last stage is between the third and fifth stages and the second stage, and is 0.48 to 0.64 times the width of the first stage. The first stage is 1.1 to 1.5 times the second stage.

On the medium pressure side, the blade and the nozzle are made of the 12% Cr-based steel shown in Table 7 above. The length of the blade portion of the moving blade in this embodiment is longer at each stage as it goes from the first stage to the last stage, and the length from the first stage to the last stage is 90 to 350 mm, and the number of stages is 6 to 6 depending on the output of the steam turbine. There are nine stages, and the length of the wing of each stage is 1.10 to 1.25, which is longer than the length adjacent to the upstream side on the downstream side.

The implanted portion of the moving blade has a larger diameter than the portion corresponding to the stationary blade, and its width is related to the blade length and position of the moving blade. The ratio of the width to the blade length of the rotor blade is the largest in the first stage, 1.35 to 1.80 times, the second stage is 0.88 to 1.18 times, and the third to sixth stages are the final stages. It is smaller and is 0.40 to 0.65 times. The high-to-medium pressure integrated turbine for a steam turbine power plant equipped with two low-pressure turbines connected in tandem in this embodiment has a distance between bearings of about 5.7 m and the blade length of the last stage blade of the low-pressure turbine ( The ratio of the distance between bearings to 168 mm) is 5.7.

Also in this embodiment, the bearing portion is provided in the third embodiment.
In the same manner as described above, a low-alloy steel overlay welding layer is provided.

FIG. 13 is a sectional view of a low-pressure turbine of 3600 rpm and FIG. 14 is a sectional view of its rotor shaft.

The low-pressure turbine has one main steam of 538 ° C./5
Coupled in tandem to a high medium pressure of 66 ° C. The moving blades 41 have six stages on the left and right sides and are substantially symmetrical on the left and right, and stationary blades 42 are provided corresponding to the moving blades. The blade length of the last stage is 4
It is 6 inches and uses a Ti-based alloy. The Ti-based alloys shown in Examples 1 and 2 are used. In particular, it contains A16%, V6% and sn2% by weight. Further, the same rotor shaft 43 as that of the second embodiment is used. Ni 3.75%, Cr 1.75%, Mo 0.4%, V
0.15%, C 0.25%, Si 0.05%, Mn 0.10
%, A forged steel having a fully tempered bainite structure of a super clean material consisting of the remaining Fe. A 12% Cr steel containing 0.1% Mo is used for each of the moving blades and stationary blades other than the last stage and the preceding stage. 0.25% cast steel is used for the inner and outer casing materials. The center-to-center distance of the bearing 43 in this embodiment is 7000 mm, the diameter of the rotor shaft corresponding to the stationary blade portion is about 800 mm, and the diameter of the rotor blade implantation portion is the same for each stage. The distance between the bearing centers for the rotor shaft diameter corresponding to the vanes is about 8.8.

In the low pressure turbine, the axial width of the root portion of the blade implantation is the smallest in the first stage, and the number of stages in the lower stage is the same in the second and third stages, and the fourth and fifth stages are the same, and gradually increases in the four stages. The width of the last stage is 6.2 to 7.0 times larger than the width of the first stage. A few steps are 1.15 to 1.40 times the first step,
4,5 stage is 2.2-2.6 times of 2-3 stage, last stage is 4,5
It is 2.8 to 3.2 times the stage. The width of the root portion is indicated by a point connecting the extended line extending to the diameter of the rotor shaft.

In this embodiment, the blade length of the rotor blades increases in each stage from the initial stage of 4 ″ to the final stage of 46 ″. Within 1270mm, up to 8 steps,
The wing length of each stage is longer within a range of 1.2 to 1.9 times as long as the downstream side is adjacent to the upstream side.

The root portion of the rotor blade has a larger diameter than the portion corresponding to the stationary blade, and has a wider end. The width of the blade is greater as the blade length of the rotor blade is larger. The ratio of the width to the blade length of the rotor blade is from 0.30 to 1.5 from the first stage to the last stage, and the ratio gradually decreases from the first stage to the last stage before the last stage. Is between 0.15 and 0.15
It gradually decreases within the range of 0.40. The last stage has a ratio of 0.50 to 0.65.

The erosion shield in this embodiment is provided in the same manner as in the second embodiment.

In addition to the present embodiment, the steam inlet temperature of the high- and medium-pressure steam turbine is 610 ° C. or higher, the steam inlet temperature to the low-pressure steam turbine is about 400 ° C., and the outlet temperature is about 1000 ° C.
The same configuration can be applied to a MW class large-capacity power plant.

The high-temperature high-pressure steam turbine power plant in this embodiment is mainly composed of a boiler, high-medium-pressure turbine, low-pressure turbine, condenser, condensate pump, low-pressure feedwater heater system, deaerator, booster pump, feedwater pump, high-pressure feedwater. It is composed of a heater system. That is, the ultra-high-temperature and high-pressure steam generated in the boiler enters the high-pressure side turbine and generates power, and is then reheated in the boiler again to enter the medium-pressure side turbine and generate power. The high- and medium-pressure turbine exhaust steam enters the low-pressure turbine and generates power, and then condenses in the condenser.
This condensate is sent to the low pressure feed water heater system and deaerator by the condensate pump. The feedwater degassed by this deaerator is sent to a high-pressure feedwater heater by a booster pump and a feedwater pump to be heated, and then returned to the boiler.

Here, in the boiler, the feedwater passes through a economizer, an evaporator, and a superheater to become high-temperature and high-pressure steam. On the other hand, the boiler combustion gas that heated the steam exited the economizer,
Enter the air heater to heat the air. Here, the feedwater pump is driven by a feedwater pump drive turbine that operates with the extracted steam from the medium pressure turbine.

In the high-temperature high-pressure steam turbine plant configured as described above, the temperature of the feedwater exiting the high-pressure feedwater heater system is much higher than the feedwater temperature in the conventional thermal power plant. The temperature of the combustion gas exiting the economizer will also be much higher than in conventional boilers. Therefore, heat is recovered from the boiler exhaust gas so as not to lower the gas temperature.

Table 7 above shows the chemical compositions (% by weight) used for the main parts of the high and medium pressure turbines and low pressure turbines of this embodiment. In this embodiment, the rotor shaft having the high pressure side and the medium pressure side integrated with each other is C 0.11%, Si 0.0
2%, Mn 0.45%, Ni 0.50%, Cr 11.21
%, Mo 0.25%, W 2.78%, V 0.20%, Nb
0.07%, Co 1.50%, N 0.025%, B 0.01
Except that martensitic steel consisting of 6% and the balance of Fe was used, those shown in Table 7 were used, and the coefficient of thermal expansion was 12 × 10 ⁻⁶ / ° C. having a ferrite crystal structure. There were no problems due to the differences.

In this embodiment, a high-medium pressure turbine and one low pressure turbine are connected to one generator tandem to constitute a tandem compound double flow type power plant. As another embodiment, two low-pressure turbines are connected in tandem, and can be configured in the same manner as in the present embodiment for power generation of an output of 1050 MW class. A higher strength shaft is used as the generator shaft. In particular, C 0.15 to 0.30%, Si 0.1 to 0.3
%, Mn 0.5% or less, Ni 3.25 to 4.5%, Cr 2.
0.5 to 3.0%, Mo 0.25 to 0.60%, V 0.05 to 0.5%
A fully tempered bainite structure containing 0.20%,
Room temperature tensile strength 93 kgf / mm ² or more, especially 100 kgf / mm
It is preferable that the FATT is ² or more and the 50% FATT is 0 ° C. or less, particularly -20 ° C. or less.
85 AT / cm or less, P, S, as impurities
The total amount of Sn, Sb and As is 0.025% or less, Ni / C
Those having an r ratio of not more than 2.0 are preferred.

Table 7 described above is similarly used for the main parts of the high-medium pressure turbine and the low pressure turbine of this embodiment. In this embodiment, by using martensitic steel around the other rotating portion of the high / intermediate pressure integrated rotor shaft integrating the high pressure side and the medium pressure side, a thermal expansion coefficient of 12 × Since it was 10 ⁻⁶ / ° C., there was no problem due to the difference in thermal expansion coefficient.

In the present embodiment, the high-to-medium pressure integrated rotor shaft was prepared by melting the above-mentioned heat-resistant cast steel by 30 tons in an electric furnace.
The carbon is vacuum deoxidized, cast into a mold, and forged to produce an electrode rod. Electroslag is remelted as the electrode rod so that it melts from the upper part to the lower part of the cast steel, and the rotor shape (diameter 1450 mm, length (For example, 5000 mm). This forging is performed at 1150 ° C to prevent forging cracks.
The test was performed at the following temperature. After annealing the forged steel,
It is obtained by heating to 050 ° C., water spray cooling, quenching, tempering twice at 570 ° C. and 690 ° C., and cutting into a predetermined shape. In addition, Cr-M
o A low-alloy steel build-up weld layer is applied.

The low pressure turbine for a steam turbine power plant having two low pressure turbines connected in tandem in this embodiment has a total bearing distance of 13.9 m, and the blade length of the last stage rotor blade of the low pressure turbine. The ratio of the distance between the bearings of the two low-pressure turbines connected in tandem to
3 and the rated output (MW) of the power plant
The ratio of the total distance (mm) of the bearing distances of the two low-pressure turbines connected in tandem to 23.1 is 23.1.

In the present embodiment, the low-pressure turbine for a steam turbine power plant having a high-medium pressure integrated turbine in which a high-pressure turbine and a medium-pressure turbine are integrated and one low-pressure turbine has a bearing distance of about 6 m. The ratio of the last stage blade of the turbine to the blade length is 5.5, and the distance between bearings of one low pressure turbine (mm) relative to the rated output (MW) of the power plant is the distance between bearings of one low pressure turbine. ) Is 10.0.

Although the high / medium pressure integrated rotor shaft in this embodiment has a center hole in any rotor shaft, in particular, P0.010% or less, S0.005% or less, As 0.005% or less, Sn0 or less. 0.005% or less, Sb
By setting the content to 0.003% or less, the center hole can be eliminated by high purification in any of the examples. The power plant of this embodiment can be applied to 3000 rpm, and the blade length of the last stage blade is 52 inches or 5 inches.
Applicable to 6 inches.

[0135]

According to the present invention, the target tensile strength of 110 kg / mm ² or more can be secured as a Ti-based alloy for the final stage rotor blade of a low-pressure steam turbine in a large forged product having a large influence of the mass effect. On the other hand, more than 43 inches, 3000rpm
, A steam turbine long blade of 50 inches or more is possible, and a larger capacity as a steam turbine power plant with a steam temperature of 538 to 660 ° C. is possible, and higher efficiency is achieved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a relationship between an aging temperature for obtaining a target tensile strength of a solution-cooled water-cooled material and a solution-solution temperature.

FIG. 2 is a diagram showing a relationship between an aging temperature and a solution heat temperature for obtaining a target tensile strength of a solution heat impinging coolant.

FIG. 3 is a diagram showing a relationship between an aging temperature and a solution heat temperature for obtaining a target tensile strength of a solution-cooled water-cooled material after rough working of dovetil.

FIG. 4 is a diagram showing a relationship between an aging temperature and a solution heat temperature at which a target tensile strength of a solution heat impinging coolant after rough working of dovetil is obtained.

FIG. 5 is a diagram showing the relationship between the tensile strength of 1 / 2t and 1 / 4t.

FIG. 6 is a diagram showing a relationship between impact absorption energy and tensile strength.

FIG. 7 is a diagram showing a relationship between impact absorption energy and tensile strength.

FIG. 8 is a perspective view of a steam turbine blade.

FIG. 9 is a side view of the low-pressure turbine blade.

FIG. 10 is a cross-sectional view in which a high-pressure turbine and an intermediate-pressure turbine are connected.

FIG. 11 is a sectional view of a low-pressure steam turbine.

FIG. 12 is a sectional view of a high-medium pressure turbine.

FIG. 13 is a sectional view of a low-pressure steam turbine.

FIG. 14 is a sectional view of a rotor shaft for a low-pressure steam turbine.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... 1st bearing, 2 ... 2nd bearing, 3 ... 3rd bearing, 4 ... 4th
Bearing, 5: Thrust bearing, 10: First shaft packing, 1
DESCRIPTION OF SYMBOLS 1 ... 2nd shaft packing, 12 ... 3rd shaft packing, 13 ... 4th shaft packing, 14 ... High-pressure diaphragm, 1
5: Medium pressure diaphragm, 16: High pressure blade, 17: Medium pressure blade, 18
... High-pressure internal casing, 19 ... High-pressure external casing, 20 ... Medium-pressure internal first casing, 21 ... Medium-pressure internal second casing, 22 ... Medium-pressure external casing, 23 ... High-pressure axle, 24 ... Medium pressure Axle, 25 ... flange, elbow, 26 ... front bearing box, 27 ... bearing part, 28 ...
Main steam inlet, 29: Reheat steam inlet, 30: High pressure steam exhaust port, 31: Cylinder connecting pipe, 33: High and medium pressure axle, 38: Nozzle box (high pressure first stage), 39: Thrust bearing wear cutoff device, 40 … Warm-up steam inlet, 41… rotor blade, 42… stationary blade, 4
3 ... bearing, 44 ... rotor shaft, 51 ... wing, 52 ...
Wing implant, 53: pin insertion hole, 54: erosion shield, 55: tie boss, 57: continuous cover.

Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) C22F 1/00 683 C22F 1/00 683 691 691B 692 692A (72) Inventor Shinya Konno 7-chome, Omikamachi, Hitachi City, Ibaraki Prefecture No. 1 Inside Hitachi, Ltd.Hitachi Research Laboratory (72) Inventor Shigeyoshi Nakamura 7-1-1, Omikacho, Hitachi City, Ibaraki Prefecture Inside Hitachi, Ltd.Hitachi Research Laboratory (72) Inventor Takeshi Onoda Hitachi City, Ibaraki Prefecture 3-1-1, Machi-cho F-term (reference) in Hitachi, Ltd. Thermal and Hydropower Division 3G002 EA06

Claims (14)

[Claims] 1. A steam turbine blade having a blade portion and a dovetail, wherein the blade length is 3000 rpm.
52 inches or more at m or 3600 rpm
At least room temperature tensile strength of the dovetil is at least 100 kg / mm ^{2 and at} least 96% of the room temperature tensile strength of the wing. And steam turbine blades. 2. A steam turbine blade having a blade portion and a dovetail, wherein the blade has a weight of Al 4-8%, V 4-8%.
And a Ti-based alloy containing 1 to 4% of Sn and having a tensile strength (x) at room temperature of 100 kg / mm ² or more and a V-notch impact value (y) at room temperature of (−0.022x
+ 4.10) or more, or the wing has a room temperature tensile strength (x) of 105 kg / mm.
V notch impact value (y) of ² or more and room temperature is (−0.02)
x + 3.98) or more (kg-m), and wherein the room temperature tensile strength of the dovetil is 96% or more of the room temperature tensile strength of the blade section. 3. A steam turbine blade having a blade portion and a dovetail, wherein the blade length is 3000 rpm.
52 inches or more at m or 3600 rpm
43 inches or more, and Al 4 to 10 by weight.
%, V4 to 10% and Sn1 to 5%, and the wing has a room temperature tensile strength (x) of 105 kg /.
mm notch impact value (y) of not less than ² mm and room temperature is (−0.0
2x + 3.98) or more (kg-m), or the dovetil has a room temperature tensile strength (x) of 100 kg / mm ² or more and a V-notch impact value at room temperature.
(y) is equal to or more than a value (kg-m) obtained by (0.022x + 4.10), a steam turbine blade. 4. A method of manufacturing a steam turbine blade made of a Ti-based alloy having a blade portion and a dovetail, after hot-forging the blade material, shown in FIG. 1 of the present application (aging temperature, solution temperature).
A (605 ° C., 855 ° C.) and B (590 ° C., 79
0 ° C), C (410 ° C, 790 ° C) and D (410 ° C,
855 ° C.). A method for manufacturing a steam turbine blade, comprising performing a solution treatment and an aging treatment of heating and then water cooling within a range connecting four points (855 ° C.). 5. A method of manufacturing a steam turbine blade made of a Ti-based alloy having a blade portion and a dovetail, wherein the (aging temperature,
The region represented by (solution solution temperature) is E (52) shown in FIG. 2 of the present application.
5 ° C, 855 ° C), F (510 ° C, 790 ° C), G (41
A method for manufacturing a steam turbine blade, comprising performing a solution treatment and an aging treatment in which heating and then blast cooling are performed within a range connecting four points of 0 ° C, 790 ° C) and H (410 ° C, 855 ° C). 6. A method of manufacturing a steam turbine blade made of a Ti-based alloy having a blade portion and a dovetil, before the final heat treatment, the dovetil portion is roughly machined to a state close to a final shape, and then shown in FIG. J (685 ° C., 855 ° C.) and K (585 ° C., 790) expressed in aging temperature and solution temperature.
C), L (410 C, 790 C), M (410 C, 85
(5 ° C.), a solution treatment and an aging treatment of heating and water cooling within a range connecting the four points (5 ° C.). 7. In a method of manufacturing a steam turbine blade made of a Ti-based alloy having a blade portion and a dovetil, before the final heat treatment, the dovetil portion is roughly machined to a state close to a final shape, and then shown in FIG. N (575 ° C., 855 ° C.), O (560 ° C., 790 ° C.)
° C), P (410 ° C, 790 ° C), Q (410 ° C, 85
(5 [deg.] C.), a solution treatment and an aging treatment of heating and then blast cooling in a range connecting four points. 8. The method according to claim 4, wherein said T
The i-base alloy is Al 4 to 8%, V 4 to 8% and Sn
A method for manufacturing a steam turbine blade, comprising a Ti-based alloy containing 1 to 4%. 9. A steam turbine power plant comprising a high-pressure turbine, a medium-pressure turbine and a low-pressure turbine, wherein the last-stage moving blade of the low-pressure turbine has a blade portion and a dovetail, and the blade portion length is equal to the rotation speed of the blade. It is made of a Ti-based alloy having a tensile strength at room temperature of not less than 52 inches or 3000 inches at 43 inches or more at 3600 rpm, and having a tensile strength at room temperature of 100 kg / mm ² or more. A steam turbine power plant having a tensile strength of 96% or more. 10. A steam turbine power plant comprising a high-pressure turbine, a medium-pressure turbine and a low-pressure turbine, wherein the last-stage moving blade of the low-pressure turbine has a blade portion and a dovetail, and the blade has a weight of Al 4 to 8%. , V4-8% and Sn
The Dovetil has a tensile strength at room temperature of 100 kg / mm ² or more and a V-notch impact value (y) at room temperature obtained by (−0.022x + 4.10). kg-m) or more, or the wing has a tensile strength (x) at room temperature of 105 kg / mm ² or more and a V-notch impact value (y) at room temperature determined by (−0.02x + 3.98) ( kg-m) or more, and the tensile strength at room temperature of the dovetail is 96% or more of the tensile strength at room temperature of the wing portion. 11. A steam turbine power plant comprising a high-pressure turbine, a medium-pressure turbine and a low-pressure turbine, wherein a last-stage moving blade of the low-pressure turbine has a blade portion and a dovetail, and the blade portion length is equal to the rotation speed of the blade. At least 52 inches at 3000 rpm or at least 43 inches at 3600 rpm, by weight, Al4 to 10%, V4
A Ti-based alloy containing 10% to 10% and Sn 1 to 5%,
The wing has a room temperature tensile strength (x) of 105 kg / mm ² or more and a room temperature V notch impact value (y) of (−0.02x + 3.0.
98) or more, or the dovetil has a room temperature tensile strength (x) of 100.
kg / mm ² or more and V-notch impact value at room temperature (y) is (-
0.022x + 4.10) (kg-
m) or more. 12. A low-pressure steam turbine having a rotor shaft, a moving blade implanted on the rotor shaft, a stationary blade for guiding the flow of steam to the rotating blade, and an inner casing holding the stationary blade. The last stage rotor blade of the low pressure turbine has a wing portion and a dovetil, and the wing portion length is 52 inches or more for the rotation speed of the blade of 3000 rpm or 43 inches or more for the rotation speed of 3600 rpm, A low-pressure steam turbine comprising a Ti-based alloy having a tensile strength at room temperature of 100 kg / mm ² or more and 96% or more of the tensile strength at room temperature of the blade section. 13. A low-pressure steam turbine having a rotor shaft, a rotor blade implanted on the rotor shaft, a stationary blade for guiding the flow of steam to the rotor blade, and an internal casing for holding the stationary blade. The moving blade has a double flow structure having six or more stages symmetrically to each other, and the last stage moving blade has a blade portion and a dovetail, and the blade has a weight of Al4 to 8%, V4 to 8%.
And a Ti-based alloy containing 1 to 4% of Sn and having a tensile strength at room temperature of 100 kg / mm ² or more and a V notch impact value (y) at room temperature of (-0.022x + 4.10).
(Kg-m) or more, or the wing has a room temperature tensile strength (x) of 105 kg / mm ² or more and a V notch impact value (y) at room temperature of (−0.02x + 3.98). (Kg-m) or more, and the tensile strength of the dovetail at room temperature is 9% of the tensile strength of the wing at room temperature.
A low-pressure steam turbine characterized by being at least 6%. 14. A low-pressure steam turbine comprising a rotor shaft, a moving blade implanted on the rotor shaft, a stationary blade for guiding the flow of steam to the rotating blade, and an inner casing for holding the stationary blade. The moving blade has a double flow structure having at least eight stages symmetrically to each other, the last stage moving blade has a wing portion and a dovetail, and the wing portion length is 3000 rpm.
52 inches or more at m or 3600 rpm
43 inches or more, and Al 4 to 10 by weight.
%, V4 to 10% and Sn1 to 5%, and the wing has a room temperature tensile strength (x) of 105 kg /.
mm notch impact value (y) of not less than ² mm and room temperature is (−0.0
2x + 3.98) or more (kg-m), or the dovetil has its room temperature tensile strength (x).
Is not less than 100 kg / mm ² and V notch impact value at room temperature (y)
Is equal to or more than a value (kg-m) obtained by (−0.022x + 4.10).